New records of the distribution and conservation status of the endangered limpet Patella ferruginea in Sardinia (Italy, W Mediterranean)

1. Patella ferruginea is an endemic and endangered limpet of the Mediterranean Sea. Its distributional range has been greatly reduced over the past century, mainly as a consequence of human pressure on coastal habitats, and its presence is now confined to a few sites in the western Mediterranean basin. 2. It was assumed that the island of Mal di Ventre was the only location hosting P. ferruginea in the central-western area of Sardinia (Italy), but reports from local people and the discovery of empty shells in surrounding areas suggested its distribution range may be greater than previously thought. 3. Several systematic surveys for the presence of P. ferruginea were conducted during the summers of 2013 and 2014 at different locations of central-western Sardinia to improve knowledge about its conservation status and to verify various reported occurrences. 4. Findings from this study confirm the critical status of conservation of the species in central-western Sardinia. The island of Mal di Ventre was confirmed as the main location hosting P. ferruginea and only one new small nucleus of limpets was found in a hardly accessible site on the coastline of the Sinis Peninsula (Cape San Marco). This nucleus represents the new southern distribution limit of the species in Sardinia. 5. This work highlights the importance of awareness-raising activities and local environmental knowledge ('citizen science') as a source of information that can result in a better understanding of the distribution of this endangered species. Hardly accessible sites represent ideal locations to put in place conservation measures for the local P. ferruginea population but further studies, specifically aimed at determining the larval dispersal and connectivity among different limpet nuclei, are required.